Receptor Binding Fitting Program

Greetings...
We are doing some receptor binding assays and which to find a good program
which will fit one and two site displacement curves, as well as do saturation
curves and scatchards.
We have looking at PCLigand and AccuFit (Lundon) which seem to fit
generally well, but unfortunately, they are pretty archaic and are a pain to
use. We have also looking at GraFit for Windows which is easy to use and
manipulate and produces nice output. Unfortunately, GraFit is a general
purpose graphing utility and thus does not have the specific equations we
need.
Are there any other programs out there, preferably windows compatible (we
have a LOT of data and most of it is analyzed in windows first), that will do
this is a reliable manner??? We are using a Beckman LSC-6500 whit a data
capture buffer. If the program has the capability of reading in raw data,
then that much the better, but that would just be a bonus.
Please E-Mail me with the name, manufacturer, and price of anything you
have seen which might do the trick.
Thanks
Michel